city signal
Live Dallas police and fire dispatch on one map — urgency-weighted, real-time, and built on zero API keys.
A real-time map of active Dallas police calls and fire-rescue incidents, fused from two public city feeds. Every incident gets an urgency-recency-severity score; markers are colored by priority, shrink and fade as calls age, and pulse when something urgent just happened. Related police and fire incidents are matched by proximity, and each call links out to the live dispatch audio for its division.
The engineering is the fun part: Server-Sent Events push diffs to the browser, and the server only polls the city feeds while at least one client is connected. Geocoding runs on the free Census batch endpoint with a Nominatim fallback, plus a custom normalizer that speaks Dallas dispatch shorthand — “MARVIN D LOVE FWY NB” resolves like a street address because the code knows what dispatchers mean.
Full case study in progress — artifacts pending clearance or writing time. The insight below is already earned.
Real-time doesn't require a paid stack. Open data, open geocoders, open tiles — and a server that only polls while someone is actually watching.
the insight